The whole idea behind adding the switch is that you SHOULD be able to switch from one bios to the other even if you had a bad flash. This assumes that you DID try booting on both sides before flashing, right?
To be honest, I found that the tutorial you pointed to didn't work out for me. With the switch in the grounded position, the xbox booted, but with it in the 3.3V position, it fragged even before I tried flashing. I thought I miswired it, but after checking it out, it still fragged. I then put the wire into a +5V point and voila, both sides booted fine and I proceeded to flash away.
I've done the same with 3 other 1.0 boxes and never had a problem with flashing.
My suggestion is to check the middle pin in both switch positions. If the box boots in the ground position, you can reflash the bad part after you move the 3.3V to a 5V source. If not, then the three wire boot trick may work. Otherwise, its modchip time.
BTW, the flash time should be less than a minute and the process finishes almost immediately after the progress bar fills up the box.
This post has been edited by Allegro1: Jan 17 2006, 07:07 PM